It is well known that a packed tower or column is often the most efficient contacting apparatus for liquid-gas contacting operations. However, in many such operations, the fluid passing through the packing bed will contain suspended or slurried solid particles which tend to accumulate on the packing or the packing support, resulting eventually in plugging of the tower.
Such plugging problems occur, for example, when a packed tower is used for cleaning a gas stream containing particulate material by liquid scrubbing of the gas stream. Plugging also occurs when a packed tower contactor is used to carry out a chemical process in which a component of a gas stream is reacted with a liquid to yield a solid reaction product in particle form. For example, in flue gas scrubbing with an aqueous solution or suspension of limestone or the like to remove sulfur dioxide, a calcium sulfate slurry is formed which causes plugging problems. Another example is a liquid phase oxidation process for removal of hydrogen sulfide from a gas stream in which the treating or scrubbing liquid is an oxidizing solution that effects oxidation of hydrogen sulfide to elemental sulfur particles that cause plugging of the packed tower.